Silver Falls Timber Company 2-6-2 "Prairie" Locomotives in the USA

Class Details by Steve Llanso of Sweat House Media

Class 103 (Locobase 15236)

Data from Baldwin Locomotive Works Specification for Engines as digitized by the DeGolyer Library of Southern Methodist University, Vol 71, pp. 384+ and Vol 80, pp. 134+. Works numbers were 55482 in June 1922 and 59137 in April 1926.

These oil-burning Prairie saddle tanks followed the first two Baldwin Mikados into service on the SFTC's 60 lb/yard (30 kg/metre) rail. They were smaller and followed a superheated design that had been sold to several other northwest logging companies. Their relatively generously scaled 9 1/2 in (241 mm) piston valves supplied steam to the cylinders.

After the SFTC closed in 1938, the 103 and 104 were sold to the brutally named Alaska Junk Company. Sometime in the 1940s, the Peninsula Terminal Railroad bought the engines and operated them for two more decades. When the PTR was done with them in the mid-1960s, it sold both to the Black Hills Central tourist road in May 1965 and July 1967, respectively. 103 was later stored as non-operational while the 104 remains in service.

Principal Dimensions by Steve Llanso of Sweat House Media
Locobase ID15,236
RailroadSilver Falls Timber Company
Number in Class2
Road Numbers103-104
Number Built2
Valve GearWalschaert
Locomotive Length and Weight
Driver Wheelbase (ft / m) 9.50 / 2.93
Engine Wheelbase (ft / m)25.33 / 7.72
Ratio of driving wheelbase to overall engine wheebase 0.38
Overall Wheelbase (engine & tender) (ft / m)25.33 / 7.72
Axle Loading (Maximum Weight per Axle) (lbs / kg)
Weight on Drivers (lbs / kg)105,000 / 47,627
Engine Weight (lbs / kg)134,500 / 61,008
Tender Loaded Weight (lbs / kg)
Total Engine and Tender Weight (lbs / kg)134,500
Tender Water Capacity (gals / ML)1800 / 6.82
Tender Fuel Capacity (oil/coal) (gals/tons / ML/MT)750 / 2.80
Minimum weight of rail (calculated) (lb/yd / kg/m)58 / 29
Geometry Relating to Tractive Effort
Driver Diameter (in / mm)44 / 1118
Boiler Pressure (psi / kPa)165 / 11.40
High Pressure Cylinders (dia x stroke) (in / mm)17" x 24" / 432x610
Tractive Effort (lbs / kg)22,109 / 10028.49
Factor of Adhesion (Weight on Drivers/Tractive Effort) 4.75
Heating Ability
Firebox Area (sq ft / m2)74 / 6.87
Grate Area (sq ft / m2)16.30 / 1.51
Evaporative Heating Surface (sq ft / m2)804 / 74.69
Superheating Surface (sq ft / m2)188 / 17.47
Combined Heating Surface (sq ft / m2)992 / 92.16
Evaporative Heating Surface/Cylinder Volume127.52
Computations Relating to Power Output (More Information)
Robert LeMassena's Power Computation2690
Same as above plus superheater percentage3201
Same as above but substitute firebox area for grate area14,530
Power L15500
Power MT346.44

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